|Publication number||US4836929 A|
|Application number||US 07/165,902|
|Publication date||Jun 6, 1989|
|Filing date||Mar 9, 1988|
|Priority date||Mar 11, 1987|
|Also published as||DE3872548D1, EP0281940A1, EP0281940B1|
|Publication number||07165902, 165902, US 4836929 A, US 4836929A, US-A-4836929, US4836929 A, US4836929A|
|Inventors||Hans Baumann, Samuel Stucki|
|Original Assignee||Bbc Brown Boveri Ag|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Non-Patent Citations (2), Referenced by (69), Classifications (33), Legal Events (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Water treatment for special plants in which extreme conditions relating to purity in chemical, physical and biological terms have to be fulfilled.
The invention relates to the provision of extremely pure water, predominantly for rinsing purposes in the manufacture of semiconductor components for the electronics industry. The feed water to be provided for such purposes imposes maximum requirements on purity, freedom from organic constituents, microbes, salts and gases. Equipment for desalination, softening, filtration, degasification, removal of organic constituents, sterilization and disinfection is therefore necessary.
In particular it relates to a process for breaking down organic substances and/or microbes in pretreated feed water for high-purity water recirculation systems using ozone which is generated in the anode space of an electrochemical cell provided with a solid electrolyte and which is brought into contact with the substances and/or microbes contained in the feed water, with a particular residence time being maintained.
In addition to the classical filtration and softening, treatment with ozone or irradiation in the ultraviolet region plays an important part in water treatment. In connection with the manufacture of highly integrated cirucits in the electronics industry, the requirements imposed on rinsing water have been increased again. The permissible values for microbe counts and residual oxygen contents have been reduced further. The state of the art of high-purity water recirculation systems, including pretreatment of the water, has been described in numerous references (cf. R.A. Hango, "Deionized Water System", Solid State Technology, 1983, July, pages 107-111).
The ultraviolet radiators usually employed for sterilization are effective only in the path of the rays from the lamp and do not therefore represent an absolutely reliable protection. Although ozone treatment would eradicate this disadvantage, it introduces undesirable oxygen into the circulation system. The synergetic action of ozone and ultraviolet irradiation has been described (of., for example, R. Barker and F.M. Taylor "Oxydation of 2-propanol in Dilute Aqueous Solution by UV/Ozone", Poceedings of the Int. Conf., - The Role of Ozone and Waste-water Treatment, London, 13-14th November 1985).
It is known that oxygen is reduced by hydrogen at room temperature in the presence of catalysts (palladium), water being formed (cf. inter alia, F. Martinola, S. Oeckl and P. Thomas, "Catalytic Reduction of Oxygen in Water", Vom Wasser 65, 1985, pages 163-72, Translation).
Electrochemical cells containing a solid electrolyte in the form of a membrane composed of a plastic polymer (ion exchange) and suitable proceses for producing gaseous products have been described in numerous references. Such cells may advantageously be used to produce ozone (cf., for example, U.S. Pat. No. A 4,416,747; EP-B-0,068,522; H.P. Klein and S. Stucki, The Production of Ozone by Electrolysis and its Application in high purity Water Systems, Conference Proceedings, 7th Ozone World Congress, pages 110-115, 9th-12th September 1985, Tokyo).
The processes and equipment described above in general no longer meet the constantly increasing requirements for high-purity water circulation systems. There is therefore a need to refine the processes and develop them further.
Accordingly, one object of this invention is to provide a process for breaking down organic substances or microbes, or both, in the feed water of high-purity water recirculation systems, which process meets the increased requirements imposed on rinsing water in the manufacture of electronic components in relation to freedom from organic constituents, microbes, oxygen in any form and any harmful reaction products. The process should be simple, reliable in operation and inexpensive and should be notable for reproducible results.
This object is achieved by the process mentioned in the introduction which comprises exposing the feed water additionally to an ultraviolet irradiation after the residence time has elapsed.
Furthermore, this object is achieved by the process mention in the introduction wherein the feed water is mixed additionally with a part of the hydrogen generated in the cathode space of the electrochemical cell after the residence time has elapsed, the residual oxygen left in the feed water and the residual ozone being reacted with the hydrogen in a manner such that said components are completely broken down to form water.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing.
Referring now to the drawing, the figure shows a diagrammatic flow chart of the process. One is the feed water supply (untreated water), which is indicated by an arrow, to the pretreatment equipment 2 (feedwater treatment). Depending on the requirement, this may comprise one or more filters, water softening apparatuses, desalination and reverse osmosis, ion exchangers etc. and any combination of such equipment.
From here, the water is fed to an electrochemical cell 3 which is provided with a solid electrolyte 4 in the form of a membrane composed of a plastic polymer. In the anode space 5, oxygen and ozone are liberated and in the cathode 6 - hydrogen. The anodically generated O2 and O3, which leaves the anode space 5 with the H2 O, is designated with the reference symbol 7, and the cathodically produced H2, which is drawn off from the cathode space 6, is designated with the reference symbol 8. 9 is a valve for venting O2 and O3 if applicable, and 10 is equipment connected thereto for converting O3 into O2. The water is now fed into the residence time container 11 in which, for example, organic substances and/or microorganisms are subjected to exposure to O2 and O3 and are broken down. This is followed by the reaction vessel 12 for ultraviolet irradiation (indicated by undulated arrow h v) in which OH radicals are produced by reaction of H2 O with O3, the excess O.sub. 3 is reduced to O2 and microbes are destroyed. The water is now fed into the reaction vessel 13 in which the O2 and O3 is broken down at room temperature by means of adding H2 while exposing to a catalyst (for example palladium). The H2 may preferably be drawn from the cathode space 6 of the electrochemical cell 3 (reference symbol 8). Optionally, extraneous hydrogen may be supplied in accordance with the broken line and reference symbol 20. 14 is a mixed bed (ion exchanger) which retains a part of the reaction products. The remainder of the latter is retained in the filter 15. 15 may comprise an ultrafiltration stage and/or a reverse osmosis stage. The arrow 16 represents the final water provided (high-purity water) which is now fed to the receiver 17. 18 is the waste water drain tapped off from the receiver 17. A part of the used water is returned to the pretreatment equipment 2 via a water return line 19.
The apparatuses 12 and 13 are placed between broken lines since they may be used optionally individually or in combination, i.e. 12 or 13 may also each be omitted.
The process according to variant A was carried out in a pilot plant in which the reaction vessel 13 containing catalyst for breaking down O2 and O3 was absent. Accordingly, no cathodically generated H2 (8) or extraneous hydrogen (20) was supplied in this case.
The pretreatment equipment 2 comprised an apparatus for reverse osmosis, a mixed bed with cation -anion exchanger and a filter. The untreated water 1 fed in was softened beforehand and fully desalinated. The electrochemical cell 3 containing solid electrolyte 4 (plastic polymer having the trade name ("Nafion" supplied by Du Pont) has an electrode area of 3 cm2. It was supplied with a quantity of water of 100 l/h and operated with a current of 4A (current density 1.33 A/cm3) with the application of a total voltage of 3.95 V. Under these conditions, an O2 concentration of 9.4 mg/l and an O3 concentration of 2.2 mg/l were established in the previously degasified water. The residence time container 11 had a capacity of 1,300 ml. This resulted in a residence time of 47 s. The reaction vessel 12 for UV irradiation comprised a quartz glass container with a capacity of 1,320 ml, which was provided with a mercury vapour low-pressure radiator TNN 15/32 manufactured by Heraeus (Germany). The water was then fed into the mixed bed (ion exchanger) 14, which had a capacity of 1,950 ml (Ultrapure Type supplied by Sybron Barnstead). The final water purifying equipment provided was a filter 15. In the present case, this was a candle filter of the type PFT-08-10-UN-15 manufactured by Brunswick with a retention capability of 0.8 μm. The plant was operated in a manner such that no water return 19 took place. 100% of the water, which was saturated with air, and consequently also with oxygen, was fed via the feed water supply 1 to the pretreatment equipment 2. For this reason, the O3 concentration downstream of the electrochemical cell was only 1.6 mg/l, while the O2 concentation adjusted itself to approx. 10 mg/l. Downstream of the reaction vessel 12 for ultraviolet irradiation, the O3 concentration was still 0.02 mg/l. By way of experiment, 2 ppm of 2-propanol were added to the feed water in order to investigate the breaking down of total organic carbon.
The process according to variant B was carried out in a larger plant which contained all the equipment designated in the figure, including reaction vessel 13 containing catalyst for breakign down O2 and O3. Accordingly, H2 (8) generated cathodically in the electrochemical cell 3 was supplied to the reaction vessel 13.
The plant was dimensioned for a water flow rate of 10 m3 /h, referred to the electrochemical cell 3. The latter had an electrode area of 4 dm2 and was operated with a current level of 400 A, which corresponded to a current density of 1 A/cm2. The cell voltage was 3.8 V. The residence time container 11 had a capacity of 150 l, so that the average residence time was approx. 54 s. The reaction vessel 12 for ultraviolet irradiation, which was provided with 5 mercury-vapour low-pressure high-current lamps, had a capacity of 160 l. The reaction vessel 13 containing a noble metal catalyst had a content of 160 l and comprised a bed of plastic carriers which were coated with palladium. In the present case, this was a product having the trade name "Lewatit OC1045" manufactured by Bayer, Germany. The mixed bed 14 containing ion exchangers had a capacity of 200 l. After it had passed through the filter 15, the high-purity water 16 was supplied to the receiver 17, a manufacturing plant for semiconductor chips. The plant was operated in a manner such that 90% of the water flowing through the electrochemical cell 3 was fed back via the water return line 19 to the pretreatment equipment 2, while 10% was fed into the circulation system as untreated water via the feed water supply 1.
The gas balance of the plant was as follows:
______________________________________At the output of the Concentration (mg/l)equipment O.sub.3 O.sub.2 H.sub.2______________________________________Cell (3) 2.15 9.65 0UV reaction vessel (12) 0.01 10.5 1.31Cathodic reaction vessel 0 0.02 0(13)______________________________________
The process according to variant C was carried out in a smaller plant in which no reaction vessel 12 for ultraviolet irradiation was present. The water was essentially treated with ozone, the excess of elementary oxygen carriers being broken down by reduction with cathodically generated H2.
The plant was dimensioned for a water flow rate of 800 l/h, referred to the electrochemical cell 3. The latter had an electrode area of 25 cm2 and was operated with a current level of 30 A. This corresponded to a current density of 1.2 A/cm2. The cell voltage was 3.9 V. The residence time container 11 had a capacity of 11 l, so that the average residence time was approx. 50 s. The reaction vessel 13 containing noble metal catalyst had a capacity of 12 l The active mass was a product having the trade name Lewatit, manufactured by Bayer. The mixed bed 14 fitted with ion exchangers had a capacity of 16 l.
The plant was operated in a manner such that, after a prior start-up phase, 100% of the water flowing through the electrochemical cell 3 was fed back to the pretreatment equipment 2 via the water return line 19, while the supply of untreated water via the feed water supply 1 was prevented. The gas balance of the plant was as follows:
______________________________________At the output from Concentration (mg/l)the equipment O.sub.3 O.sub.2 H.sub.2______________________________________Cell (3) 2.2 9.4 0Residence time 1.6 9.8 1.43container (11)Catalytic reaction 0 0.02 0vessel (13)______________________________________
The invention is not restricted to the exemplary embodiments.
The requirement for maintaining a particular minimum residence time after charging the water with ozone (after passing through the electrochemical cell 3) is not tied to the presence of a residence time container 11 intended specifically for this purpose. If only small amounts of water are circulating, or on the other hand, long pipe lines are required, the residence time container 11 may turn out to be comparatively small or may be omitted completely, in particular, with sufficiently high turbulence in the circulation system.
In addition, it is not always necessary to pass the entire quantity of water treated in the pretreatment equipment 2 through the electrochemical cell 3. A part which depends on the requirements may be tapped off downstream of the pretreatment equipment 2 and supplied directly to the residence time container 11: by-pass (not drawn in in the Figure -). On the other hand, a part of the O2 or O3 (any excess which occurs), which is dissolved and/or present as bubbles, may be drawn off from the water after the outlet from the electrochemical cell 3, and fed via the valve 9 to equipment 10 for converting O3 into O2. However, additional supply of extraneous hydrogen 20 (drawn as a broken line) may also be provided at the inlet to the reaction vessel (13) containing catalyst for breaking down O2 and O3. The two last mentioned measures produce the same final effect: prevention of any oxygen content in elementary form in the final high-purity water for the receiver 17. The residence time container 11 and the reaction vessel 12 for ultraviolet irradiation may be combined in one and the same common vessel, so that the ozone is brought into contact with the substances and/or microbes contained in the water simultaneously with and at the same place as, the ultraviolet irradiation.
In principle, the process can be carried out with ultraviolet radiation alone or with O2 and O3 breakdown by means of H2 alone or using both process steps simultaneously. The reaction vessels 12 and 13 have therefore been placed between vertical broken lines in the figure.
Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3822786 *||Jun 30, 1972||Jul 9, 1974||Marschall K||Apparatus for treating and purifying sewage, particularly sewage contaminated with detergents|
|US3925176 *||Oct 10, 1973||Dec 9, 1975||Adolph P Okert||Apparatus and method for electrolytic sewage treatment|
|US4179347 *||Feb 28, 1978||Dec 18, 1979||Omnipure, Inc.||System for electrocatalytic treatment of waste water streams|
|US4218315 *||Sep 11, 1978||Aug 19, 1980||Hartkorn Karl Heinz||Oxidation and adsorption method for removing contaminating substances from liquids|
|US4311569 *||Apr 21, 1980||Jan 19, 1982||General Electric Company||Device for evolution of oxygen with ternary electrocatalysts containing valve metals|
|US4416747 *||Apr 29, 1982||Nov 22, 1983||Bbc Brown, Boveri & Company Limited||Process for the synthetic production of ozone by electrolysis and use thereof|
|US4548716 *||Jul 25, 1984||Oct 22, 1985||Lucas Boeve||Method of producing ultrapure, pyrogen-free water|
|US4735728 *||Nov 28, 1986||Apr 5, 1988||Environmental Tech America, Inc.||Method for pollution control in photographic processing|
|DE3243817A1 *||Nov 26, 1982||Jul 5, 1984||Hager & Elsaesser||Process for producing aseptic pure water|
|EP0242533A1 *||Feb 23, 1987||Oct 28, 1987||Ozonia AG||Method and apparatus for conditioning feed-water by means of ozone for reverse osmosis|
|GB2136790A *||Title not available|
|JPH06185386A *||Title not available|
|1||Nebel et al., "Purification of Deionized Water by Oxidation with Ozone," Solid State Technology, vol. 27, No. 10, Oct., 1984, pp. 185-193.|
|2||*||Nebel et al., Purification of Deionized Water by Oxidation with Ozone, Solid State Technology, vol. 27, No. 10, Oct., 1984, pp. 185 193.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5073268 *||Dec 11, 1990||Dec 17, 1991||Ebara Corporation||Process and system for purifying pure water or ultrapure water|
|US5130032 *||Jul 12, 1990||Jul 14, 1992||Sartori Helfred E||Method for treating a liquid medium|
|US5180502 *||May 13, 1991||Jan 19, 1993||Permelec Electrode Ltd.||Electrolytic ozonizer and method of decomposing ozone-containing waste gas using said ozonizer|
|US5190627 *||Apr 24, 1992||Mar 2, 1993||Ebara Corporation||Process for removing dissolved oxygen from water and system therefor|
|US5205994 *||Sep 4, 1991||Apr 27, 1993||Permelec Electrode, Ltd.||Electrolytic ozone generator|
|US5217607 *||Feb 21, 1992||Jun 8, 1993||Diamond Water Systems, Inc.||Water decontamination system with filter, electrostatic treatment and UV radiation chamber|
|US5250177 *||Jul 5, 1991||Oct 5, 1993||Samsung Electronics Co., Ltd.||Water purifier with an ozone generating device|
|US5302298 *||Jun 13, 1990||Apr 12, 1994||Wedeco Umwelttechnologien Wasser Boden Luft Gmbh||Process and installation for treating liquids charged with pollutants|
|US5336413 *||Mar 16, 1993||Aug 9, 1994||E.M. Engineering F.T.S. B.V.||Process and apparatus for the purification of water|
|US5445741 *||Dec 23, 1993||Aug 29, 1995||Solvay Deutschland Gmbh||Process for treating waste water|
|US5529683 *||Mar 20, 1995||Jun 25, 1996||United Technologies Corp.||Method for preventing degradation of membranes used in electrolytic ozone production systems during system shutdown|
|US5607572 *||Mar 21, 1995||Mar 4, 1997||Ceramatec, Inc.||Removal of oxygen from inert gases|
|US5635039 *||Nov 23, 1994||Jun 3, 1997||Lynntech, Inc.||Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same|
|US5670094 *||Jan 25, 1996||Sep 23, 1997||Ebara Corporation||Method of and apparatus for producing ozonized water|
|US5779912 *||Jan 31, 1997||Jul 14, 1998||Lynntech, Inc.||Photocatalytic oxidation of organics using a porous titanium dioxide membrane and an efficient oxidant|
|US5797216 *||May 15, 1995||Aug 25, 1998||Reznik; David||Apparatus and methods for reducing the redox potential of substances|
|US5915161 *||Sep 25, 1995||Jun 22, 1999||Amphion International, Limited||Microbe stunning device for a biological decontamination system|
|US5951839 *||Sep 13, 1994||Sep 14, 1999||Reznik; David||Method of producing a water-based fluid having magnetic resonance of a selected material|
|US5965093 *||Jul 7, 1995||Oct 12, 1999||Amphion International, Limited||Decontamination system with improved components|
|US5993749 *||Nov 13, 1995||Nov 30, 1999||Amphion International, Limited||MISE fluid treatment device|
|US6086057 *||Jun 24, 1998||Jul 11, 2000||Tadahiro Ohmi And Organo Corporation||Method and device for preparing cleaning solution|
|US6090296 *||Mar 17, 1999||Jul 18, 2000||Oster; Stephen P.||Method and apparatus for UV-oxidation of toxics in water and UV-disinfection of water|
|US6117335 *||Feb 23, 1998||Sep 12, 2000||New Star Lasers, Inc.||Decontamination of water by photolytic oxidation/reduction utilizing near blackbody radiation|
|US6117337 *||Jun 11, 1998||Sep 12, 2000||Lynntech, Inc.||Enhanced photocatalytic oxidation of organics using a porous titanium dioxide membrane|
|US6136186 *||Jul 14, 1998||Oct 24, 2000||Lynntech, Inc.||Photocatalytic oxidation of organics using a porous titanium dioxide membrane and an efficient oxidant|
|US6149810 *||Jan 20, 1998||Nov 21, 2000||Lynntech, Inc.||Membrane with supported internal passages|
|US6156211 *||Jul 14, 1998||Dec 5, 2000||Lynntech, Inc.||Enhanced photocatalytic conversion of methane to methanol using a porous semiconductor membrane|
|US6200466||Jul 16, 1999||Mar 13, 2001||New Star Lasers, Inc.||Decontamination of water by photolytic oxidation/reduction utilizing near blackbody radiation|
|US6383361||Nov 14, 2000||May 7, 2002||Proton Energy Systems||Fluids management system for water electrolysis|
|US6409928||Oct 5, 2000||Jun 25, 2002||Lynntech, Inc.||Photocatalytic oxidation of organics using a porous titanium dioxide membrane and an efficient oxidant|
|US6458257||Feb 9, 1999||Oct 1, 2002||Lynntech International Ltd||Microorganism control of point-of-use potable water sources|
|US6509305 *||May 12, 2000||Jan 21, 2003||Tadahiro Ohmi||Method for preparing cleaning solution|
|US6527942 *||Mar 19, 2001||Mar 4, 2003||Siemens Aktiengesellschaft||Conditioning system and method for reducing the oxygen content of water carried in a subsystem of an industrial plant|
|US6589396 *||Jun 25, 1999||Jul 8, 2003||Canon Kabushiki Kaisha||Method for treating colored liquid and apparatus for treating colored liquid|
|US6620210||May 14, 2002||Sep 16, 2003||Lynntech, Inc.||Method of washing laundry using ozone to degrade organic material|
|US6776886||Apr 9, 2003||Aug 17, 2004||Canon Kabushiki Kaisha||Method for treating colored liquid and apparatus for treating colored liquid|
|US6860976||Dec 10, 2001||Mar 1, 2005||Lynntech International, Ltd.||Electrochemical apparatus with retractable electrode|
|US6866806||Sep 30, 2002||Mar 15, 2005||Lynntech International, Ltd.||Methods for assembling an electrochemical cell|
|US6964739||Dec 12, 2001||Nov 15, 2005||Tersano Inc.||Device and method for generating and applying ozonated water|
|US7008880 *||Feb 10, 2004||Mar 7, 2006||Renesas Technology Corp.||Method for fabricating semiconductor integrated circuit device|
|US7053007 *||May 19, 2005||May 30, 2006||Renesas Technology Corp.||Method for fabricating semiconductor integrated circuit device|
|US7449090||Sep 22, 2004||Nov 11, 2008||Lynntech, Inc.||Electrochemical apparatus with retractable electrode|
|US8361384||Aug 3, 2009||Jan 29, 2013||Aardvark Ip Holding, Llc||Water treatment device and methods of use|
|US9156714 *||Feb 6, 2015||Oct 13, 2015||Concurrent Technologies Corporation||Energy generation system and related uses thereof|
|US9187344||Nov 28, 2012||Nov 17, 2015||Silver Bullet Water Treatment Company, Llc||Water treatment device and methods of use|
|US9321665||Apr 11, 2012||Apr 26, 2016||Silver Bullet Water Treatment Company, Llc||Water treatment systems and methods|
|US9611160||Jul 2, 2013||Apr 4, 2017||Vws (Uk) Ltd.||Wastewater treatment apparatus and method|
|US9617177||Sep 25, 2015||Apr 11, 2017||Silver Bullet Water Treatment Company, Llc||Water treatment device and methods of use|
|US9650270||Mar 9, 2016||May 16, 2017||Silver Bullet Water Treatment Company, Llc||Water treatment systems and methods|
|US9850148||Jan 28, 2015||Dec 26, 2017||Silver Bullet Water Treatment Company, Llc||Water treatment systems and methods|
|US20020005385 *||May 3, 2001||Jan 17, 2002||Stevens Donald B.||Water treatment systems and methods|
|US20020134674 *||Dec 10, 2001||Sep 26, 2002||Andrews Craig C.||Electrochemical apparatus with retractable electrode|
|US20030201159 *||Apr 9, 2003||Oct 30, 2003||Canon Kabushiki Kaisha||Method for treating colored liquid and apparatus for treating colored liquid|
|US20040161945 *||Feb 10, 2004||Aug 19, 2004||Yoshikazu Tanabe||Method for fabricating semiconductor integrated circuit device|
|US20050058886 *||Sep 22, 2004||Mar 17, 2005||Andrews Craig C.||Electrochemical apparatus with retractable electrode|
|US20050208731 *||May 19, 2005||Sep 22, 2005||Yoshikazu Tanabe||Method for fabricating semiconductor integrated circuit device|
|US20050236278 *||Nov 1, 2004||Oct 27, 2005||Steven Shoup||Fresh water generation system and method|
|US20090071838 *||Oct 14, 2008||Mar 19, 2009||Lynntech, Inc.||Electrochemical apparatus with retractable electrode|
|US20150151983 *||Feb 6, 2015||Jun 4, 2015||Concurrent Technologies Corporation (Ctc)||Energy generation system and related uses thereof|
|USRE38130||Nov 14, 1997||Jun 3, 2003||Amphion International Limited||Biological decontamination system|
|CN104159852A *||Jan 17, 2013||Nov 19, 2014||电解臭氧股份有限公司||水净化系统|
|DE4104094A1 *||Feb 11, 1991||Aug 13, 1992||Rudolf Gesslauer||Procedure and device for pre-clearing waste liq. such as pig slurry - after removal of coarse solid material, water undergoes ozonisation and electrolysis in prepn. for biological treatment|
|DE4125541A1 *||Aug 1, 1991||Feb 6, 1992||Nippon Rensui Kk||Vorrichtung und verfahren zum reinigen von wasser|
|EP0342169A2 *||May 10, 1989||Nov 15, 1989||Permelec Electrode Ltd||Electrolytic ozonizer and method of decomposing ozone-containing waste gas using said ozonizer|
|EP0342169A3 *||May 10, 1989||Apr 11, 1990||Permelec Electrode Ltd||Electrolytic ozonizer and method of decomposing ozone-containing waste gas using said ozonizer|
|EP0738236A1 *||Sep 13, 1994||Oct 23, 1996||David Reznik||Apparatus and method for reducing the redox potential of substances|
|EP0738236A4 *||Sep 13, 1994||Dec 3, 1997||David Reznik||Apparatus and method for reducing the redox potential of substances|
|WO1999062828A1 *||May 24, 1999||Dec 9, 1999||Proton Energy Systems||Fluids management system for water electrolysis|
|WO2012093284A3 *||Dec 22, 2011||Aug 23, 2012||VWS (UK) Limited||Wastewater treatment apparatus and method|
|U.S. Classification||210/638, 210/764, 210/669, 210/760, 205/629, 210/748.12, 210/748.15|
|International Classification||C02F1/42, C02F9/00, C02F1/58, C02F1/78, C02F1/44, C02F1/50, C02F1/20, C02F1/46, C02F1/467, C02F1/70, C02F1/32|
|Cooperative Classification||C02F2101/30, C02F2303/18, C02F2201/46115, C02F1/4672, C02F2201/4618, C02F1/20, C02F1/444, C02F2001/427, C02F1/441, C02F2201/782, C02F2103/04, C02F2303/04, C02F1/32, C02F2201/4612|
|Apr 3, 1989||AS||Assignment|
Owner name: BBC BROWN BOVERI AG, SWITZERLAND
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:BAUMANN, HANS;STUCKI, SAMUEL;REEL/FRAME:005036/0974
Effective date: 19880228
|Nov 17, 1992||FPAY||Fee payment|
Year of fee payment: 4
|Jan 25, 1994||AS||Assignment|
Owner name: CUSTOM METALCRAFT, INC. 2332 EAST DIVISION, MIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MAY, LINDY L.;REEL/FRAME:006939/0935
Effective date: 19940112
|Nov 19, 1996||FPAY||Fee payment|
Year of fee payment: 8
|Dec 26, 2000||REMI||Maintenance fee reminder mailed|
|Jun 3, 2001||LAPS||Lapse for failure to pay maintenance fees|
|Aug 7, 2001||FP||Expired due to failure to pay maintenance fee|
Effective date: 20010606